Apparatus for casting composite cast rolls

ABSTRACT

An apparatus for casting composite cast rolls which have a hard outer shell and a soft core, comprises a bottom molding box which has a lower roll pin cavity for forming the lower roll pin and which supports a permanent mold for the roll body which has a molding part with an upper roll pin cavity for forming the upper roll pin part. A pouring conduit is connected laterally and tangentially into the bottom molding box for pouring the outer shell material into the mold. The bottom molding box is supported on a trestle and it has a slide valve with an opening for discharging the excess shell material from the bottom of the cavity after the solidification of the desired thickness of the shell. A refractory tubular drain brick is connected between the slide valve and the lower portion of the lower roll pin cavity, and it is filled with granular refractory material, such as sand. The drain brick is covered with a thin refractory plate which has a marginal thin edge which rests on the granular refractory material at the top of the drain brick and completely closes the interior of the drain brick.

United States Patent 1 3,881,545 Braultmann et al. May 6, 1975 APPARATUSFOR CASTING COMPOSITE 57 ABSTRACT CAST ROLLS An apparatus for castingcomposite cast rolls which [75] Inventor Hein Di t B k D i have a hardouter shell and a soft core, comprises a W lf Haflwig Rheinkamp, bottommolding box which has a lower roll pin cavity Baerl, both of Germany forforming the lowerroll pin and which supports a permanent mold for theroll body which has a molding [73] Asslgnee' Rhemstahl Glebere' partwith an upper roll pin cavity for forming the [22] Filed: Feb, 4, 1974upper roll pin part. A pouring conduit is connected laterally andtangentially into the bottom molding box [21] Appl' 439527 for pouringthe outer shell material into the mold. The bottom molding box issupported on a trestle and it 52 us. on 164/349; 164/94 has a slidevalve with an Opening for discharging the [51] Int. Cl. B22c 9/28 excessShell at ial fr m the bottom of the cavit [58] Field of S h 1 4/3 3 3 43 5 366, after the solidification of the desired thickness of the164/23, 91, 108, 353, 354, 355, 356, 94, 95 shell. A refractory tubulardrain brick is connected be- 348 349 350 351 tween the slide valve andthe lower portion of the lower roll pin cavity, and it is filled withgranular re- [56] R f e Cit d fractory material, such as sand. The drainbrick is cov- UNITED STATES PATENTS ered with a thin refractory platewhich has a marginal thin edge which rests on the granular refractorymate- 1 33: 3; i rial at the top of the drain brick and completelycloses 3'279002 10/1966 Meves ....I:::::..............:::::.... 164/337the interior Ofthe drain brick- Primary Examiner-Francis S. HusarAssistant Examiner-John S. Brown Attorney, Agent, or Firm-McGlew andTuttle 6 Claims, 2 Drawing Figures APPARATUS FOR CASTING COMPOSITE CASTROLLS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates in general to the construction of molds and, inparticular, to a new and useful apparatus for casting composite castrolls which have a hard outer shell and a soft core, and which includesa drain brick which is filled with a granular refractory material and iscovered by a thin cover which completely closes the interior of thebrick.

2. Description of the Prior Art The known devices for casting rollswhich have a hard shell and a soft core comprises a bottom molding boxfor shaping the lower roll pin and a permanent mold which rests on thebottom box and serves to shape the roll body. The apparatus alsoincludes a mold part inserted into the permanent mold and serves toprovide the shape of the upper roll pin. A pouring conduit or funneltube leads laterally to a tangential ingate of the bottom box. Thebottom box is supported by a trestle and is provided at its base with aslide valve below which a ladle is located. In operation with the slidevalve closed, the shell material is filled into the mold through thepouring gate up to the level of the roll body and thereafter, uponsolidification of the shell in the desired thickness, the slide valve isopened and the remaining still molten portion of the shell material isdischarged into the ladle. Finally, the slide valve is closed again andthe core material is filled in.

In the known arrangements, a tubular drain brick is set in the base ofthe bottom box defining a communication between the mold cavity and theopening of the slide valve which is lined with a refractory material. Inorder to prevent the shell material from penetrating into the drainbrick during the filling of the mold to a location where it wouldinstantly solidify because of the small cross-section, the interior ofthe drain brick, as well as that of a portion of the refractory-linedslide valve opening which is adjacent to the drain brick, is filled upwith a granular refractory material. This granular refractory materialmust be selected very carefully. In any case, it must be completely dry.It must neither sinter with the molten iron nor become agglomerated, andit must remain fluid to be able to immediately flow out as soon as thevalve is opened and to clear the passage section. A choking of the drainbrick may endanger the entire casting because, unlike ladles which aresometimes provided with similar slide valves, the choking in this caseis difficult to remedy because of the trestle and the ladle underneathwhich impedes the access to the opening. In addition, it may happen thatthe drain brick has to be very long, for example 30 to 60 cm, if a shortroll pin is to be provided. Among materials suited for the filling ofthe drain brick and the adjacent portion of the slide valve opening, dryquartz sand has proved to be very convenient. Experience has shown,however, that there is a danger of the sand being washed out of thedrain brick by the cast material which enters through the lateralpouring gate and consequently, there is a danger that the molten ironpenetrating into the drain brick and solidifying therein in a short timewill form a plug which hinders a free passage of the shell material.

SUMMARY OF THE INVENTION The present invention provides a mold apparatusfor forming roll pins of different layer hardness, which comprises adrain brick which is filled with a refractory material which is coveredby a refractory plate of small thickness which rests on the granularrefractory material and completely closes the interior of the brick.This cover plate which completely shields the filling of the drain brickand advantageously fits flush with the upper border thereof prevents theiron from getting into and solidifying with the brick.

In a development of the invention, the refractory cover plate isprovided on its bottom surface with notches which preferably extend in adiametrical direction. These notches define rated break lines tofacilitate the breaking up of the plate while the supporting sandfilling is permitted to run out upon the opening of the slide valve.

According to a further development of the invention, the drain brick isflared upwardly, similar to a funnel. For such a construction, the drainbrick is advantageously formed in two separate parts, one a funnelshapedpart, and one a cylindrical part, and each such design is arranged topermit assembly of drain bricks of different lengths with the samefunnel part. The funnel part of the drain brick makes it possible to usea larger refractory cover plate which under the weight of the metalcolumn permits the breaking up of the plate in a corresponding bettermanner. In addition, the funnel facilitates the outflow of the materialin excess.

Another advantageous feature of the invention is the provision of aburnable alcoholic liquid black wash on the upper surface of the coverplate as well as of the drain brick. This wash is burnt off immediatelyupon its application. After drying up, the black wash forms a sealingconnection between the cover plate and the drain brick so that the plateis securely held in place against the infiowing iron which, inconsequence, cannot penetrate between the cover plate and the drainbrick. It is important to burn off the coating of black wash immediatelyafter its application in order to prevent any portion of the liquid frompassing between the plate and the brick into the loose sand where itwould be held back and become disturbant, for example, causing theformation of lumps, etc.

Accordingly, it is an object of the invention to provide an improvedcasting apparatus having a bottom molding box with a roll pin cavity forforming a lower roll pin and a permanent mold for the roll body having amolding part with an upper roll pin cavity overlying the lower roll pincavity and which includes a slide valve arranged at the lower end of thelower roll pin cavity having a tubular drain brick therein which isfilled with a granular refractory material and which is covered by acover plate which rests on the refractory material and is flush with thetop of the drain.

A further object of the invention is to provide a casting apparatuswhich includes a drain pipe arranged at the lower end of the cavitywhich is filled with a refractory material and which is closed at itsouter end by a valve which may be opened after casting and wherein thedrain pipe includes a cover having break lines thereon defining weakenedareas to permit the fractionating of the plate during the discharge ofthe material from the mold.

A further object of the invention is to provide a casting apparatuswhich is simple in design, rugged in construction and economical tomanufacture.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a vertical sectional view of the lower portion of a castingapparatus for casting rolls constructed in accordance with theinvention; and

FIG. 2 is an enlarged bottom plan view of the cover plate shown in FIG.1.

GENERAL DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawingsin particular, the invention embodied therein, comprises a castingapparatus, generally designated 50, having a lower end portion whichincludes a bottom mold box 1 having a lower roll pin cavity 2 thereinfor forming the lower roll pin portion of a roll. A permanent mold ortop mold portion 4 includes an upper roll pin cavity 5 which overliesthe cavity 2 and is concentrically arranged in respect thereto. Cavity 2is formed centrally within a compacted lining portion 9 which iscompacted around a drain pipe or drain brick, generally designated 8,which extends to the lower end of box 1 and whose top surface issubstantially flush with a level 9a of the compacted lining. Drain brick8 extends through a fixed portion 6a of a slide valve, generallydesignated 6, which includes a central moving portion 6b and a lowerfixed portion 60. Valve 6 includes an operating mechanism 7 in the formof a piston rod movable in the directions indicated by arrows 7a toshift intermediate parts 6b so-that the opening therethrough 52 may bepositioned to either align with or moved out of alignment with a drainopening 54.

In the embodiment of the invention shown, the refractory brick 8 is madeup of a tubular portion 8a of uniform cylindrical configuration and atop portion or filling portion 812 which is made in the shape of afunnel with a wider mouth portion at its top. The upper edge of upperpart 8b is flush with the compacted lining level 9a of bottom box 1.

In accordance with the invention, drain pipe 8 is filled with a fillingmaterial, such as a quartz sand filling 10, and the top of the drainpipe is closed by a cover 11, having an inner portion 11a which fitsthrough the opening at the top of funnel section 8b of drain pipe 8 andwhich also includes a thin top rim 1 lb which is positioned over the topend of drain pipe 8, and is substantially flush with lining level 9a.The sand 10 in the drain pipe is dry quartz sand.

In accordance with the invention, cover plate 11 is of ceramic material,such as a fireproof clay and it makes a tight closure with the top ofdrain pipe 8. The plate may be made relatively thin, for example, from 3to 5 mm, and it is provided on its bottom surface with two relativelydeep grooves 12 of from I to 2 mm deep which define break linesextending along the diameters. In the embodiment shown, two such breaklines which intersect at right angles are provided.

In accordance with a further feature of the invention, the upper surfaceof cover plate 1 l and the upper front face of drain brick 8b are coatedwith a burnable alcoholic liquid black wash 13 which is burnt offimmediately after its application in order to prevent any penetration ofthe liquid into the quartz sand fillingl0.

The material for casting is the outer shell of the roll pin and isdirected into the lower mold cavity 2 through a fill line opening 14which defines a tangential ingate through which the casting material issupplied to the mold.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. An arrangement for casting composite cast rolls having a hard shelland a soft core, comprising a bottom molding box having a lower roll pincavity for forming the lower roll pin, a permanent mold for the rollbody having a molding part with an upper roll pin cavity for the upperroll pin and which overlies the lower roll pin cavity, a pouring conduitfor the shell material connected laterally into said bottom molding box,a trestle supporting said bottom molding box, a valve connected to thelower end of said bottom mold box and having an opening for dischargingthe excess shell material after the solidification of the desiredthickness of the shell to be formed, a refractory tubular drain brickconnected between said slide valve and said lower roll pin cavity andbeing filled with a granular refractory material and being located inthe bottom of said bottom molding box, and a thin refractory platecovering said drain brick and resting on the granular refractorymaterial flush with the top surface of said drain brick and completelyclosing the interior of said drain brick.

2. An arrangement for casting composite cast rolls, according to claim1, wherein the bottom surface of said refractory cover plate is providedwith a notch defining a break line.

3. An arrangement according to claim 1, wherein said refractory coverplate includes a bottom surface having a plurality of notches extendingdiametrically there-along and defining break lines.

4. An arrangement according to claim 1, wherein said drain brick isflared upwardly and outwardly to form a filling funnel at the topthereof.

5. An arrangement according to claim 1, wherein said drain brickcomprises a funnel-shaped upper portion and a cylindrical lower portion.

6. An arrangement according to claim 1, including a coating of burnablealcoholic liquid black wash over said cover plate and the top face ofsaid drain brick which is burnt off immediately after its application.

1. An arrangement for casting composite cast rolls having a hard shelland a soft core, comprising a bottom molding box having a lower roll pincavity for forming the lower roll pin, a permanent mold for the rollbody having a molding part with an upper roll pin cavity for the upperroll pin and which overlies the lower roll pin cavity, a pouring conduitfor the shell material connected laterally into said bottom molding box,a trestle supporting said bottom molding box, a valve connected to thelower end of said bottom mold box and having an opening for dischargingthe excess shell material after the solidification of the desiredthickness of the shell to be formed, a refractory tubular drain brickconnected between said slide valve and said lower roll pin cavity andbeing filled with a granular refractory material and being located inthe bottom of said bottom molding box, and a thin refractory platecovering said drain brick and resting on the granular refractorymaterial flush with the top surface of said drain brick and completelyclosing the interior of said drain brick.
 2. An arrangement for castingcomposite cast rolls, according to claim 1, wherein the bottom surfaceof said refractory cover plate is provided with a notch defining a breakline.
 3. An arrangement according to claim 1, wherein said refractorycover plate includes a bottom surface having a plurality of notchesextending diametrically there-along and defining break lines.
 4. Anarrangement according to claim 1, wherein said drain brick is flaredupwardly and outwardly to form a filling funnel at the top thereof. 5.An arrangement according to claim 1, wherein said drain brick comprisesa funnel-shaped upper portion and a cylindrical lower portion.
 6. Anarrangement according to claim 1, including a coating of burnablealcoholic liquid black wash over said cover plate and the top face ofsaid drain brick which is burnt off immediately after its application.